function largestOfFour(arr) {
    // You can do this!
    const result = [];
    for (let i = 0, len = arr.length; i < len; i++) {
        result.push(Math.max(...arr[i]));
    }
    return result;
}

largestOfFour([
    [4, 5, 1, 3],
    [13, 27, 18, 26],
    [32, 35, 37, 39],
    [1000, 1001, 857, 1]
]);
